According to what is reported by La Gazzetta dello Sport in this morning's print edition, AC Milan's head coach Stefano Pioli spoke to the team yesterday. The technician is annoyed but not furious. With Sassuolo, it will be inevitable to change.
The setup with Messias, Diaz, Leao and Giroud doesn't seem to be reproducible. Also, Olivier needs rest and there are many absences like that of Davide Calabria and Theo Hernandez (fatigue, but he might recover just in time vs Sassuolo). Ismael Bennacer will be unavailable to face Sassuolo due to a disqualification and Tomori is injured.
As per the source, there are great opportunities to try out different players who are available such as these two players: Rade Krunic and Tommaso Pobega. They have good chances to play against the Neroverdi. Meanwhile, a 24-year-old centre-back is on the Rossoneri's radar, reportedly.
